1. Field of the Invention
The present invention is related to an encoding method of the screen frame and the electronic device applying the same, and more particularly to an encoding method of the screen frame adaptively changing the image quality and the electronic device applying the same.
2. Description of the Prior Art
Screen frame sharing is an important application of information technology. Examples of screen frame sharing include performing remote control with remote desktop, or wirelessly transmitting presentation slides from a computer to a projector. Typically, screen frame data, obtained by the operating system through a software program, is lossless. However, due to limited communication bandwidth, the screen frame data has to be compressed through encoding before being transmitted.
Since any loss of the image quality of the screen frame, being full of regular patterns such as rectangular frames, curves or fonts, is easily observed by a user, the requirement of the image quality of the decoded and recovered screen frame is high. Besides, as the user is primarily involved in other jobs such as remote control or presentation, the screen encoder should not occupy too many system resources so that the primary job can be run without being affected. Moreover, the shorter the latency from the screen frame being transmitted by the transmitting end to the screen frame being displayed by the receiving end, the closer the feeling of real time control of the remote user.
However, when the prior art screen encoder processes screen frames including a video region with lossless or lower loss encoding, the amount of data may exceed the capacity of network or the receiving system, causing the video to appear discontinuous due to insufficient frame rate on the receiving end. On the contrary, when the prior art screen encoder compresses the data with higher loss encoding, even the motionless region of the screen frame would have a higher loss image quality. Besides, when processed by the prior art video encoder, the regular patterns of the screen frame also has the lossy problem. In addition, the complicated algorithms adopted by the prior art video encoder, such as motion estimation and motion compensation, etc., would occupy too many system resources and incur longer latency.
Therefore, it is highly desirable that a screen frame encoding method not only utilizes less system resources, but also presents a smooth video and a higher quality motionless image simultaneously with lower latency for screen frame sharing.